The former Partick Thistle manager has raided his old workplace to sign up the duo on pre-contract agreements. And he claims the key strengths possessed by Paton and Erskine include some much-needed versatility, with right-back Paton also capable of operating in midfield, while Erskine has operated on both wings for Thistle this term, as well as a second striker.
McNamara said: "I'm delighted that they have signed on with us. They bring quality, versatility and they will improve the squad, which is the most important thing."
He added: "They are different players obviously. Paul can play a few positions. We've had problems recently fitting guys into certain positions but Paul can do that. Chris has got something different that people like to watch. He can always create something and he's scored some great goals this year and I think the United fans will take to him as well."
McNamara is busy preparing his side for Friday's Clydesdale Bank Premier League meeting with Motherwell at Fir Park.
But he admits he has already turned his attention to keeping hold of as many of his current squad as possible.
Steve Banks, Rory Boulding, Barry Douglas, Willo Flood and Marcus Tornstrad will all see their deals expire in the summer, as will skipper Jon Daly, who has been linked with a move to Irn-Bru Third Division champions Rangers.
Daly also has an offer on the table from his current employers and with Paton and Erskine on board for next season, McNamara is keen to act swiftly to get some of the others pegged down too.
He said: "I'm just glad to get Paul and Chris tied up nice and early. That's the way I like to do things. I did that last season with Partick. When we went away for the summer holidays, I had everything tied up.
"I had the squad all set so I knew exactly what was happening after we came back and that's something I want to do here. We have already spoken to certain players about extending their contracts. We are now just in the process of seeing which ones are staying and which ones will go."