And the characters don't address each other by name in any way.

Your casting idea will give you a really distinct sound.

Male, Azerbaijani or Azerbaijani accented English, probably 35 to 50, warm and intelligent.

Slightly dry, not a booming documentary narrator.

He gives the program a connection to the place.

Female, British English, perhaps late 20s to late 30s, educated and curious, warm rather than RP newsreader posh.

She should sound like a very good podcast host, somebody who clearly knows her history, but still reacts with genuine fascination.

I would not make the man's Azerbaijani accent very difficult.

Remember, nearly the entire hour is English.

A strongly accented voice can become tiring over 60 minutes and could occasionally make 11 laps a degree less natural.

I'd want something more like an Azerbaijani man who speaks extremely fluent English with a clearly detectable Azerbaijani Caucasian accent.