Can WCart email customers who haven't ordered from me in a while?

Yes, this is the Win-back tab inside Abandoned Carts (the Abandoned Cart Recovery plugin).

1. Tick Email customers who haven't ordered in a while.
2. Set No order in (days) and Don't re-email within (days) so nobody gets emailed too often.
3. Write the Email subject and Email body.
4. Optionally tick Include a comeback coupon. Each customer gets their own single-use code, either a percentage or a fixed amount, valid for the days you choose.

Click Save settings. It then runs automatically, and Run now sends to anyone who qualifies right away.