The closest one I'm aware of is "Escape from Camp 14," which is based heavily on interviews with a North Korean refugee. Because of the level of state control on communication, there isn't a lot of media coming out of the DPRK. When refugees manage to get from the DPRK to RoK, social services there tend to focus on getting them acclimated to the culture and economy of the South and helping them integrate. Not many end up doing things like learning English to the point that they could write books about it.

The US State Department has also shown little interest in North Korean refugees, so the avenues that State might open up to engage with them are not developed. If westerners want to learn about the DPRK, they have to do it through journalistic avenues without significant help from the US' or the Republic of Korea's governments. Much of the contact journalists manage to make is done through China and doesn't lead to a lot of interaction outside of heavily monitored official channels.

My access to this topic is limited by the fact that I don't speak or read Korean, so there could be materials available that I'm not aware of.