DiFelice, 37, joined Binghamton in early June largely to work as a catcher for top prospect Mike Pelfrey, who has now made four starts for New York since being promoted from the Eastern League.
The veteran backstop played in 11 games for the Mets in 2005, batting .118 (2-for-17). In 39 games with Binghamton this season, DiFelice was batting .277 (31-for-112) with one home run and 19 RBI.
DiFelice has also played for the St. Louis Cardinals, Tampa Bay Devil Rays, Arizona Diamondbacks, Kansas City Royals, Detroit Tigers and the Chicago Cubs in a major league career that dates back to 1996.
Hietpas, 27, was batting .185 (31-for-168) in 62 games at Triple-A. Considered a defensive specialist, Hietpas had two home runs and 10 RBI for the Tides, with Sandy Martinez logging most of the Tides' playing time.
The Mets may have need for a backup catcher in the coming weeks. Paul Lo Duca will have offseason surgery to repair a ligament injury in his right thumb, and Ramon Castro missed the entire series against the Atlanta Braves with an oblique injury.