The top prospects were scratched from the starting lineup 10 minutes before Friday's Triple-A Buffalo game. They will be in uniform for the Mets in Saturday night's game at the Phillies.
"We felt like we needed to change it up," general manager Omar Minaya said. "We looked internally to see what we could do to change things. We feel we're still in a pennant race and we hope they help us win some games."
Martinez, 21, heated up the past week after recently enduring a 3-for-33 rut. He was hitting .255 with 12 homers and 33 RBIs in 68 games this season with the Bisons.
Martinez said he had a restless night wondering whether he was being promoted or traded. He received the good news Saturday morning that he was returning to the Mets.
"I know everybody here. They are like my family," he said. "I didn't know nothing, but I'm very happy to be here."
Tejada was hitting .280 with one homer and 16 RBIs in Triple-A this year. He also has played in 35 games with the Mets this season, batting .212 while subbing for shortstop Jose Reyes and second baseman Luis Castillo when they were on the disabled list with injuries.
Manager Jerry Manuel said Tejada will see the bulk of his playing time at second base. Martinez will platoon in right field with Jeff Francoeur and face right-handed pitchers.
Tejada was in Saturday's starting lineup, batting eighth. Martinez was held out with lefty Cole Hamels on the mound.
"He's going to play," Minaya said of Martinez. "He's not going to be here to be on the bench."
The 34-year-old Cora was hitting .207 in 62 games for the Mets. His contract would have vested for $2 million for 2011 if he appeared in 80 games.
Feliciano, 31, was batting .292 in 27 games.
The Mets lost 7-5 at Philadelphia on Friday to fall to 6-15 since the All-Star break. They were eight games back of NL East-leading Atlanta entering play on Saturday.