Can you still track it's location after it has been wiped/erased?
No, an iOS device is no longer associated with an iCloud account after it has been restored. 

In iOS7, there is a new feature called Activation Lock[1] which prevents devices from being restored once they are associated with an account unless the correct password is used to disable the lock.

[1]http://support.apple.com/kb/ht5818

After being erased, either by you via find my phone, or buy the 'new owner' via a DFU forced restore, tracking is no longer available.

If the phone is put into DFU mode then iTunes will restore the phone.  However during activation, it will still require the original apple ID to activate, so the phone is useless, apart from selling for spare parts.