How to use "insist" in a sentence

Dombey said, "They insist the system checks out perfectly."

By this time, we had passed the one-year mark in the development process, and I knew we were not going to wind up with a usable script, so I didn't insist on discussing whether the rubber tires would melt off the vehicle within two hundred yards or three, or ponder at what point the gasoline tank might explode

'If you insist on our marriage, I'll be your faithful wife,' she said, 'but I'll never love you!'