Wells now has seven goals this season and might have had a hat-trick on Boxing Day.
Wagner said: “He knows what I expect from him. I will never be satisfied with Nahki because I believe he has a big talent.
“I will always want more from him because he is a good guy with great potential.”
Bermudan Wells scored in both halves before Emyr Hughes added a third direct from a corner. Adam Reach grabbed a consolation for Preston in the fourth minute of stoppage time.
Wells gave Town the lead in the 38th minute when Joel Lynch played the ball for Huws to set up a close-range finish.
Wells made it 2-0 in the 55th minute when he smashed home from Harry Bunn’s pass.
Wells had an effort ruled out just after half-time for offside and hit the outside of the angle of crossbar and post to miss out on his hat-trick.
He also had a shot saved later by the foot of goalkeeper Jordan Pickford.
Town sealed the points in the 76th minute when Huws, taking advantage of the swirling wind, scored direct from a corner.
Reach denied the home side a clean sheet when he fired home left-footed from close range from Paul Gallagher’s pass.
Wagner added: “The result was good, but not the performance in the first half. I’m not sure what the reason was. The conditions were difficult, especially with the wind against you, as it was for us in the first half. The table doesn’t matter as much as the performances and the results and we need to be more consistent.”
Huddersfield Town: Steer, Smith, Hudson, Lynch, Chilwell; Hogg (Paterson 86), Huws (Cranie 81), Scannell, Dempsey (Bunn 46),
Lolley; Wells. Unused substitutes: Davidson, Carayol, Murphy, Bajaj.
Preston North End: Pickford, Vermijl (Woods 67), Clarke, Huntington; Cunningham, Gallagher, Kilkenny (Brownhill 61), Johnson, Reach; Keane, Garner (Doyle 72). Unused substitutes: Wright, Welsh, Hugill, Kirkland.
Referee: C Kavanagh (Lancashire).
Man of the match: Nahki Wells.