Wellbeck had a good game, scoring one and then setting up Anderton with another with a superb back-heel.
Wayne Rooney added the third when he headed home a Ryan Giggs cross from seven yards.
"Every single point is vital. We need as many points and keep the ball rolling," Welbeck told Sky Sports.
"The tempo started fast, but some wise words from the gaffer at half-time helped.
"I think it showed how well the manager has got the squad combined. Once you are in the starting XI you have to work hard to keep your place."