The Red Devils boss has been shorn of the services of key men for long periods this season, and has seen performances suffer as a result.
United were, however, able to hand a debut to record signing Mata against Cardiff City on Tuesday and welcome strike duo Van Persie and Rooney back from injury.
Van Persie opened the scoring against the Bluebirds, at the end of a move started by Mata, and Rooney entered the fray as a second half substitute.
Moyes is confident that all three have more to offer and is looking forward to the day when he can unleash an exciting trio of attacking talent on Premier League opponents.
He told Sky Sports: "It's massive to get them back, it's so important to us.
"They are still missing a bit of match practice, but we'll keep building them up - Robin and Wayne, and Juan as well. I'm looking forward to getting them all on the pitch together."
On £37million man Mata, Moyes added: "I thought he did very well. He helped make the goal, he did some really good moments for us and I think he should be pleased tonight how he played, we were.
"He looked as though he wasn't too far away. He still needs some match practice, he's not played as much as he might have liked recently. We tried to keep him on as long as we could, hopefully that will benefit him."
Moyes was delighted to see his big guns help to down dogged Cardiff, with United showing that they can grind out results when required.
He added: "We had to get three points and we did it. We scored two, could have scored more. We didn't really have a great deal to defend against, so overall I was pleased with the performance.
"It was tense. We had other opportunities which we didn't really take. While it is only 1-0 there is always a threat that they can maybe get a goal. But we deserved our victory tonight."