I'm installing a new wall oven into a new cabinet.
Previous oven was wired with just the wire nuts exposed behind the oven; I was a bit surprised of not having an electrical box.
I was planning on just installing the correct size electrical box but I've also read that a disconnect is recommended for a 220 appliance if the panel is more than 50' or out of line-of-site (both apply).
I would go with an ordinary electrical box with no switch.
The good conscientious technician or serviceperson will carry extra oils and lubricants in case the new pump did not come with oil or the oil was accidentally spilled, so the service call can be completed without an extra visit.