The calculated distance (air line) between Tremp and La Seu d'Urgell is approximately 32 miles respectively 51 kilometers.
By car or train, the actual journey to La Seu d'Urgell is certainly longer, as only the direct route (as the crow flies) between Tremp and La Seu d'Urgell has been calculated here.
Air line (approximately)
51 kilometers
28 nautical miles