Sardinas, 22, was acquired by Milwaukee in January as part of the swap that sent pitcher Yovani Gallardo to Texas. Sardinas hit .196 with four RBI in 36 games with the Brewers this season while playing second base, shortstop and third. He batted .282 with 17 doubles, 16 steals and 33 RBI at Triple-A Colorado Springs.
The 23-year-old Flores batted .308 with 17 doubles, nine homers and 41 RBI at Triple-A this year in the New York Yankees and Seattle organizations. He made his big league debut on May 30 and hit .219 (7 for 32) in 12 games with the Yankees, who sent him to Seattle in the July trade that brought Dustin Ackley to New York.
Stearns also acquired infielder Jonathan Villar from Houston for right-hander Cy Sneed on Thursday, one day after obtaining infielder Javier Betancourt and a player to be named from Detroit for reliever Francisco Rodriguez and a player to be named.
New Mariners general manager Jerry Dipoto previously acquired right-hander Nate Karns from Tampa Bay, right-handed reliever Joaquin Benoit from San Diego, and center fielder Leonys Martin and right-handed reliever Anthony Bass from Texas.
Also Friday, Seattle designated left-hander Danny Hultzen for assignment and selected the contracts of infielder Patrick Kivlehan and outfielder Boog Powell from Triple-A Tacoma.
Hultzen, the second overall pick in the 2011 amateur draft, had shoulder surgery in October 2013 that caused him to miss the following season. The 25-year-old was 0-1 with a 3.38 ERA in three starts with Double-A Jackson this year, then went on the disabled list on May 26 because of a strained rotator cuff in his pitching shoulder and was sidelined for the rest of the season.