The only list I found appears to be old (only has DOCSIS 2.0 modems):
»www.myinsight.com/Help-broadband ··· 7105.asp
I would recommend getting a DOCSIS 3.0 modem. I currently have the Motorola SB6121, which is on TWC's approved modem list, and have the 20.0 service and everything has been rock solid.
»www.timewarnercable.com/en/resid ··· dem.html
Once you have your new modem hooked up you will need to call Insight and provide them with the MAC address so it can be provisioned on your account.