Why doesn't WAT verzekering fit here?
I can't really explain it well, but maybe this site will help. http://www.dutchgrammar.com/en/?n=Pronouns.It01
You have insurance rather than using it... unless you have multiple insurances and you have to choose between them in a particular instance.
Excactly. "Welke verzekering heb jij?" is a better translation than "Welke verzekering gebruik jij?".
Would "Wat voor een verzekering gebruiken jullie?" work here too? In the sense of "What [kind of] insurance do you use.." Thanks.