Gerrard scored in the second minute and made it 2-0 after 38 minutes with Ryan Babel adding the third seven minutes from time.
Liverpool, who have now won nine of their last 10 league matches and drawn the other, moved on to 80 points and above United on goal difference.
Third-placed Chelsea face fourth-placed Arsenal on Sunday at the Emirates Stadium and a win for United and defeat for Chelsea will mean Liverpool will be the only team still in with a mathematical chance at least, of stopping United winning a third successive title and equalling Liverpool's all-time record of 18 championships.
Gerrard struck the opener when he beat the Hammers offside trap and rounded goalkeeper Robert Green to score. He took his goal tally to 23 -- his personal best for one season -- after 38 minutes when he followed up to force the ball home after Green saved his penalty. It was Liverpool's 100th goal in all competitions this season.
The 101st came late on when Babel tapped in the rebound after Green had saved the Dutchman's header.
"We will just keep going," said West Brom manager Tony Mowbray, whose team could have been relegated on Saturday had results gone against them.
"It all rests on next week's game against Liverpool. If we can get some sort of result and take it to the last day against Blackburn then anything can happen."
Brunt made amends when he put West Brom back in front on the rebound after his penalty was saved by Wigan's substitute keeper Richard Kingson, who had replaced the injured Chris Kirkland.
