To clear room for Gale and Villanueva, who were not on the 40-man roster, the Padres designated shortstop Dusty Coleman and right-hander Jose Valdez for assignment.
"We feel like all those guys provide some real value to us for the rest of September as far as what they could mean to the future of our organization," said Padres manager Andy Green.
Renfroe was immediately inserted back into the lineup on his first day back in San Diego since his surprise August demotion. In 14 regular-season games for El Paso, Renfroe batted .509/.557/.891 with four home runs.