He is a fellow student from my university days, and we still keep in touch often.
I reunited with my fellow apprentices who trained at the same dojo.
仲間 is a common, casual word for 'companion' or 'mate' in any group; 朋輩 is more formal and often implies a structured shared background.
Standard kanji form; 朋 is ateji for this reading.
Variant kanji form; less common than 朋輩.
The kanji 朋 means 'friend' or 'companion', and 輩 means 'group' or 'fellows'. The reading ほうばい is ateji (phonetic) for 朋, while 傍輩 is a variant spelling. The word is of Chinese origin (cf. Mandarin péngbèi).