After conceding first, Chelsea overran the hosts to fire home five goals at London stadium.
Maresca said afterwards: "Very happy for today, also very happy last week. I thought the performance was good, we didn't score then but tonight we scored five.
"For me it has been fantastic since the moment I enjoyed the club. Probably the last results - Conference League, Club World Cup, top four in the Premier League. I think no-one expected but we achieved it."
Youngster Estevao Willian's error created West Ham's opener and Maresca added: "He needs to adapt, he needs to make many mistakes to understand how the Premier League is different to in Brazil.
"We conceded after he did the flick, he needs to understand but he is a fantastic player."
On Chelsea having five different goalscorers on the night, Maresca was asked if this was a sign the team is not dependent on Cole Palmer, who missed the game due to injury.
He said, "You know already how I feel, that I don't care about... You are there to say things and people, in general, they are there to say something. The ones that they say that we are just a Cole team, for sure, Cole is our best player, no doubt. For sure, when we have Cole, we are a much, much, much better team.
"But I think we already showed last year, in two or three months, where Cole, unfortunately for us, was not 100%. When we achieved top four, that no-one expected. And the most important thing, no-one asked me in the first season to finish top four in the Champions League. They asked me in two years in the Champions League."