Aguero made it 4-0 in the 86th and Sterling wrapped it up in injury time, becoming the first player since Didier Drogba in 2010-11 to score a hat-trick on the league's opening weekend.
The result means they have won their last 15 Premier League games - three short of their own record of 18 set between August and December in 2017.
The Hammers despite making a pretty bold start to the game, went 1-0 down just before the half-hour mark and from that point onwards, it was all downhill for Manuel Pellegrini's side.
Liverpool fired. City answered. When the team takes a step forward he plays better. If Liverpool who have arguably one of the best defences in Europe defend like they did on Friday night against a top 6 team they will suffer. This is going to happen many times.
City, which racked up 98 points to beat Liverpool by a point last season, rarely looked like getting out of second gear with a measured performance at London's Olympic Stadium.
Raheem Sterling loves playing and scoring against the Irons. Of course the Hammers have had some hyped arrivals in the likes of Pablo Fornals and Sebastian Haller and even though Fornals only came on from the bench in the 2nd half, he made nearly no impact except for a teasing cross.
City committed 13 fouls during their trip to the London Stadium, which was over double the amount of fouls West Ham committed. "We have to we get off to a good start". Wasn't the game supposed to be a simple one, that would include human error?
"My only wish is that VAR does not make mistakes", said the Spanish tactician.
The Video Assistant Referee system, previously used in England in the FA and League Cups, is supposed to eradicate any doubt that the right decision was taken over goals, penalties and other key moments.
"It's hard to come back against City, but we will review the game, look at what went wrong and try to put it right next week". "People will say they have VAR and it has hit his hand, but he is not looking at the ball", Coady said.