Thanks to
@Tecnico 's superior Google skills, I have a new repair kit coming from Calgary.
The dishwasher is currently finishing it's test run and I'm feeling confident enough to post a "yay, it's fixed" post before I see the proof - hearing the quiet operation is sufficient for now.
Thanks to everyone for their thoughtful suggestions and advice - much appreciated. Knowing that I had new parts coming, I decided to go half-redneck, get 'er working now, and be prepared to swap out tomorrow, next month, next decade, when-ever... I still like the stainless screws idea best if I needed a long term solution.
My solution has 3 parts. Part 1 was to use thin CA glue with accelerator to glue the flat parts together; a small amount of thin CA on the green coloured impeller component, and a light spray of accelerator on the the other half. After a few seconds cure, I was not able to pull the parts apart, but I don't trust CA long term in a hot and wet environment.
Next step was to re-form the mushroom caps on the green studs using a heated nail. At first I planned to split the studs with the nail, but switched to just smearing the tops around.
The final step was to cover the caps and fill the voids using epoxy. I had planned on using JB Weld, but was too impatient for the 15 hour cure time so went with a fast setting clear epoxy. I don't know how well it will stand up to the heat, but I suspect the mushroom caps alone will last several years.
I applied a thick coat, and cleaned up the high spots with a file afterwards - not pretty, but hopefully functional.
The dishwasher just finished its test run. No smoke in the air, no water on the floor, and clean dishes inside. Yay and thanks!