Sancho is on-loan at Chelsea this season from Manchester United.
Ahead of tonight's clash with Bournemouth, Maresca said: "For me he’s doing very well. I am quite surprised with Jadon, because I knew Jadon already (from seeing him at his previous clubs) and I know what I expected from him, but in terms of being consistent, he’s doing very well.
"Apart from a short part of the season when he had some problems, when he was out ill, then for the rest he has been very good.
"I expected him to do well, but for all the players doing well for a long period is not easy, and he has been doing well for a long period already. He’s doing well, now he just needs to continue going in that way."
On fellow winger Noni Madueke, Maresca stated: "It is not only from Noni, from all the squad.
"There are players who are doing that, like Moi (Caicedo) who since we started has been doing well. Almost all of them are doing well, but it’s not just about Noni, it’s about all the players. In the moment that they can be consistent, it is better for the team.
"I consider Noni to be one of our best players, to be honest, but because of that we want our best players to be in the right way always. No switching off, no some days that they can drop.
"It is the other way and he is doing very good with us, knowing that during a season it is normal that for some moments players are not 100 per cent. But it is not just about Noni, it is about all the players."