The hosts took the lead through Myler's boot when Wasps were penalised for offside in their own 22, but the visitors were soon level when Dave Walder slotted a penalty of his own.
However, Northampton took charge once they secured possession in the Wasps 22 in the 14th minute and hooker Dylan Hartley's clever pass sent Mujati over unopposed, Myler adding the conversion from the touchline.
Wasps lost centre Steve Kefu to injury and, after Joe Simpson thwarted Ashton with an excellent tackle, then fell further behind when they conceded a penalty try after a succession of failed scrums near their own line.
Myler added the simplest of conversions and the game was all-but won when Ashton kicked ahead and Foden won the foot race with Richard Haughton to touch down.
Wasps improved after the break but fell further behind to another Myler penalty.
Northampton secured a bonus point when Hartley sent Ashton over before replacement Commins grabbed the Saints' fifth try, Shane Geraghty converting both.
Northampton director of rugby Jim Mallinder: "We controlled the game very well and dominated in all parts. We prefer to play on hard pitches as it was today as we like it fast and open.
"It makes a big difference having all the international players back plus Lee Dickson.
"Dylan (Hartley) is maturing all the time and has the right credentials to be an England captain. He had a great game in the tight and had a hand in at least two of the tries."
Wasps boss Leo Holden: "We were beaten in all facets of the game. It is very disappointing and something not very likeable to see.
"Northampton are a very good side with their full team out and we have to go away and re-group."
Replacements: Reihana for Downey (68), Geraghty for Myler (55), Commins for Dickson (68), Waller for Tonga'uiha (57), Sharman for Hartley (68), Mercey for Mujati (64), Sorenson for Day (64), Clark for Dowson (62).
Replacements: Wallace for Kefu (21), van Gisbergen for Walder (57), Lewsey for Berry (70), French for Payne (65), Lindsay for Webber (58), Cannon for Birkett (40), Betsen Tchoua for Worsley (40). Not Used: Broster.
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