Technically, what you just drew MAY work... but it's a bad idea. There's no reason to be switching the high AND low side at once. Switching increases losses dramatically. A lot of the time, the transistor which isn't PWM'ed can be a smaller package and/or mounted without a heatsink and the driver is noncritical because the switching time is not an issue.
A lot of high side NMOS drivers pump a capacitor around, which refreshes the capacitor charge when the output is low (off). They CAN'T be given a constant-on duty cycle, the capacitor charge will decay and the gate gets into a partially turned-on state which creates very high heat. This depends on the driver, though. In that type of driver, it's a good argument for making the high side PWM'ed and the lows are only switched when direction changes.
In a simple motor-control H-bridge, you really don't need a motor control PIC. Any PIC with two PWM ports and 2 pins for the directions will drive a basic H-bridge just as well.