Stewart, who homered as a pinch-hitter in the seventh inning Tuesday before singling off Pirates closer David Bedard in the ninth inning of a 7-4 loss, hit a solo shot in the second inning Wednesday off Johan Oviedo (6-13) and delivered a two-run homer in the fifth off Ryan Borucki.
"I'm trying to be ready whenever my name is called," said Stewart, who was recalled from Triple-A Syracuse on July 4. "Fortunately, put some good swings last night and today's. Baseball's a tough game, so hopefully it can continue."
The two-homer game was the third of Stewart's career and his first since Aug. 12, 2021, when he went deep twice for the Baltimore Orioles.
Stewart has four homers in 25 games for the Mets after being limited to three big league at-bats last season with the Orioles. The 29-year-old, a first-round draft pick in 2015, made his big league debut in 2018 during current Mets manager Buck Showalter's last season as Baltimore's skipper.
"Guys come through being a first-round pick and all these great expectations and they have some periods where they may not quite get what everybody hopes they get to," Showalter said. "And then sometimes you get a good player after that's over, because at 27, 28, 29, the world's full of players who really care figuring things out a little bit. So hopefully we're seeing some of that with him."
Stewart also had a pair of pivotal plays in right field. He began the relay that resulted in Andrew McCutcheon being thrown out at home in the fifth before making an over-the-shoulder catch of Ke'Bryan Hayes' fly ball to the track with two on to end the sixth and the Mets up 6-3.
"Plays like that, you want to hit the first guy - it's the difference in being safe and out," Stewart said about the relay in which he threw to Jeff McNeil, who fired home to Omar Narváez to nab McCutcheon. "And then Jeff made a heck of a throw to get him at home. I'm honestly more proud about that than the home runs."
Pete Alonso hit his 36th homer, a solo shot that moved him into the Mets' top 10 list in RBI with 469, snapping a tie with Keith Hernandez.
The five holdovers from the Mets' opening day lineup - Nimmo, Alonso, Lindor, McNeil and Daniel Vogelbach - hit a combined .306 (15-of-49) with four homers and 11 RBI against the Pirates.
"I think these are times where veteran players establish some really good examples," Showalter said. "What you do speaks louder than what you might say."
"We were about five feet away from him hitting two homers," Pirates manager Derek Shelton said. "Good swings throughout the game for him. Just didn't get that extra five feet we needed on both of them."
Tylor Megill (7-6) earned his first win in exactly two months after giving up two runs in five innings.
Oviedo allowed four runs and walked five in four-plus innings.
DÍAZ GETTING CLOSER
Mets closer Edwin Díaz, who suffered a torn right patellar tendon in the World Baseball Classic in March, threw in a bullpen Wednesday morning. The team hasn't ruled out the possibility Díaz could pitch this season.
"I'm not going to sit here and tell you I know exactly how it's going to be and what he's going to do," Showalter said. "But he's done his part. He's been a guy that's showed up - everything we've asked of him and then some. The only thing we've had to do is slow him down some.
"I hope we have that decision to make."
THIS PIRATE TRENDS UP
Hayes went 2-for-5 and finished the season batting .444 (12-for-27) against the Mets - the highest single-season average by a Pirates player with at least 25 at-bats against New York since Gregory Polanco hit .500 in 26 at-bats in 2018.
WALK OF LIFE
The teams combined to issue 13 walks Wednesday and 27 in the three-game series.
"There were a lot of pitches thrown in this series," Shelton said.
Pirates: CF Joshua Palacios (gastrointestinal illness), who was lifted for a pinch-hitter in the seventh inning Tuesday, felt better Wednesday but didn't play.
Mets: The Mets recalled RHP Dennis Santana from Triple-A Syracuse and optioned RHP José Butto to the same affiliate. ... IF Mark Vientos (left wrist) underwent an MRI that revealed tendinitis. He is day-to-day. Showalter said Vientos was injured during his second and final at-bat Tuesday. ... LHP David Peterson, who absorbed a comebacker off his right wrist in Tuesday's start, underwent an X-ray that revealed no damage.
Pirates: Have yet to announce a starter for Friday, when Pittsburgh continues a six-game road trip by visiting the Minnesota Twins.
Mets: LHP José Quintana (0-4, 3.03 ERA) opens a four-game set at the St. Louis Cardinals. Quintana is winless in five starts despite allowing three runs or fewer each time.