Cremation is the burning of the body in a crematory furnace, and depending on where the cremation takes place, the body may be burned along with a container or coffin and the clothing the body is wearing. Jewelry is generally removed and pacemakers are always removed as they can explode and damage the crematory furnace.
The container or coffin is specially designed to be burned along with the body, and usually any additional metal objects, such as coffin handles, are removed prior to cremation. In some cultures it is mandatory that next of kin witness the body being cremated, so there are facilities designed for that religious requirement.
Destruction of our body, a gift from God, is a desecration, regardless.