The Blues prevented Newcastle United from compiling a single shot on target in Saturday's 1-0 victory at Stamford Bridge.
"We can see everyone in training working hard, we now know each other and you can see everyone improving," Zouma told the club's website.
"We want to be very difficult to beat and a very good team playing, so that is what we are trying to do and we are working hard in training on what we do on the pitch.
"It was a very good win for us, a very difficult game when you have Newcastle coming here and putting everyone at the back and trying to counter-attack. We stayed focused but the first half was a bit difficult because they were compact.
"The second half we created some more spaces and then we had more chances to score. We scored one and we could have scored more but the most important is the three points and the clean sheet as well."