Wilmington (4-8), conversely, shot 39.3 percent (22 of 56) from the field, including five straight misses during a 15-0 Miami run over a 2 minute, 23 second span in the second half.
Harris capped the run with a 3-pointer and Johnson added two free throws to give Miami a 69-55 lead with 9:53 left to play.
Wilmington, which led five times, never got any closer as the Quakers missed 14 of their last 18 shots.
Brandon Candella led Wilmington with 16 points.
Devin Williams' decision last month to sign with an agent and enter the NBA draft has left West Virginia in a tough spot.
Florida State's student government has passed a resolution discouraging Seminoles fans from wearing Native American headdresses at games.
The second annual Gavitt Tipoff Games, eight games between members of the Big East and Big Ten to be played Nov. 14-18, will feature Villanova at Purdue in the opener.