I erased my stolen iPhone instead of putting it in lost mode
You will be able to locate an erased iPhone if it's near a previously used Wi-Fi network. The thieves won't be able to use your iPhone as well.

Quoting from the Apple Support document, Find My iPhone: Erase your device:


  When you remotely erase a device, Activation Lock remains on to protect it. Your Apple ID and password are required to reactivate the device.


and


  Important: Before you erase your device, try to locate it or play a sound on it. After you erase it, you can’t use Find My iPhone to do either. You may still be able to locate your Mac or Apple Watch if it’s near a previously used Wi-Fi network.