Wiring solid state relays

Can I wire the relay like below or is there a better way? I've read that a diode is used to protect the relay but are they necessary when powering water/fuel pumps or thermo fans?

If you use it as PWM then you need a SS if you are only turning something on an off then regular relay should be fine.

are there any issues with using a single SSR to PWM two devices?

ie an electric water pump (10amps) and a radiator fan (15amps) on a 100 amp relay.

If you have enough pwm outputs I would use 1 for each. That way you could have a 3d table for each device.

On mine thermo fan is based on engine temp and car speed, water pump based on engine temp and rpm.

This is how I ended up wiring mine