U.S. Soccer Stud Abby Wambach -- CELEBRATES Gold Medal with Pizza and Beer!

Abby Wambach TRAINED HER ASS OFF to lead the U.S. soccer team to a gold medal ... and yesterday she celebrated the victory by letting herself go ... with PIZZA AND BEER!!!

Wambach was out with some pals at Paisano's Pizza in Hermosa Beach, CA ... doing a little well-deserved boozy day partying with her new best friend ... the gold medal.

FYI -- Wambach is a frickin' badass ... who got punched in the face by a cheap-shotting Colombian in one of the early rounds of the Olympics ... and GOT UP.