The Mavericks opened the roster spots by placing guard Avery Johnson on the injured list with a right calf strain and forward Popeye Jones on the list with a right ankle sprain.
Najera returns after undergoing arthroscopic surgery on his left knee on Dec. 6. He has missed 33 games and averaged 8.7 points and 5.3 rebounds in the 15 games he has played.
He says he is eager to play again and to rejoin his teammates.
"They had forgotten about me a little bit," Najera told the Fort Worth Star-Telegram. "I had to remind them."
"Najera gives us something that doesn't always end up in the stats, and that's his garbage type of mentality," forward Michael Finley told the paper. "By that I mean his willingness to do the dirty work for our team, get the rebounds, take the charges, be aggressive defensively and just give us that (physical) presence."
Eschmeyer underwent arthroscopic knee surgery in November that cleaned up cartilage and removed a tumor. He has appeared in just two games.
Jones is averaging 2.1 points in 21 games, and Johnson has averaged 3.7 points in 32 games.