To answer your question, you may be able to enter using the VWP.

Does your individual J-1 visa annotate whether or not you are you are subject to the two year foreign residence requirement?

If you are subjected to this rule, more than likely you will not be able to use the VWP. If you are not subjected to the rule, then you should likely have no problems.

The two year rule that often applies to the J-1 visa is a toughie to get around, even in family immigration cases where a spouse is applying for adjustment of status. There is a waiver you can file to get around having to remain outside of the USA for 2 years, but i'm not certain if it applies to just traveling with the VWP.

Hope that helps!