Mix pears, peaches, and pineapple in a serving bowl.

Stir pudding mix into reserved liquid from the peaches in a small saucepan over medium-low heat; cook and stir until the pudding dissolves completely and the mixture is bubbling, about 5 minutes. Pour the pudding mixture over the fruit mixture and stir to coat.

Refrigerate salad until chilled completely, at least 20 minutes.