To describe the PLA or PVA(as it was known in Korea) tactics as "wave tactics", during the Korean war would be wrong. Mass infantry assaults were just a small part of the overall tactics and strategy used by PLA/PVA commanders. A brief on the Korean War tactics are given below.
http://www.centurychina.com/history/faq2.shtml#6
To say that PLA commanders did not care about soldiers lives, would also be wrong. Chinese soldiers do happen to have mothers and families back home.
http://www.centurychina.com/history/faq2.shtml#6
PLA commanders had to plan keeping in mind their strengths and weaknesses. Superiority in manpower was their strength and they used it to their best ability.PVA's tactics were designed to void UN's advantage of air power and artillery.
PVA used night fighting tactics. It would start an attack when night fell, withdrew and went to cover at dawn, so US airplanes could not harass them. It also used close combat, threw its units into enemy line, so the enemy artillery could not operate. Another PVA tactics was to infiltrate deep into enemy positions, attack their command posts and artillery positions directly from inside.
During the truce talks, PVA invented the bunker war, they would dug very long and deep bunkers in the hills and stock supplies there, when enemy shell the hills, they would withdraw into the bunkers, when the shelling stopped, they came out to fire on the attackers, after the surface positions taken by enemy, they would withdraw back into the bunkers, then PVA artillery would shell the enemy on the surface and they came out the bunkers again to assist the retaking of the hill.
PVA's main strategy at the beginning was the so-called "movement war", the main objective was to divide the enemy into isolated pieces and then use superior strength of force to annihilate the encircled enemy piecemeal before enemy reinforcement could be brought in, to do this, PVA uses frontal attacks and simultaneous penetrations to cut directly into enemy rear, cutoff MSR (main supply route) and withdraw routes, trap enemy units when they tried to redeploy.
To say that PLA commanders did not care about soldiers lives, would also be wrong. Chinese soldiers do happen to have mothers and families back home.