A fixed preposition is part of the word. It is learned with the word, never worked out from the meaning.

Nothing about insisting suggests 'on' rather than 'for'. English fixed these pairings centuries ago and no rule regenerates them, which is why this subtopic is memory work and the cards that follow are lists rather than laws.

She insisted on an apology and objected to the delay.

each verb keeps its own preposition

She insisted for an apology and objected against the delay.

the sense fits, the pairing does not

Where it bites

Where a plausible preposition is offered. All four options in a fixed-preposition question usually make sense; only one is the pairing English actually uses.