How to flash android AOSP 10 to device?
The recovery is now built into the boot image instead of having a separate partition. So, a separate recovery image does not exist.
The files you have are supposed to be flashed to their respective partitions:

Boot to boot, 
System to system, 
Vendor to vendor, 
Vbmeta to vbmeta, 
Dtbo to dtbo

You can avoid the system_other as it is to build a dummy into your inactive boot slot. It isn't actually used. But if you want, you can flash it to the inactive slot. You check current active slot by using this command: fastboot getvar current-slot. Then flash to that slot by adding the slot suffix (example: If current slot is a, flash it to b - fastboot flash system_b system_other.img

Remember that you need to perform a wipe of internal storage from either fastboot (fastboot -w) or by going into the Android Recovery mode.