a shoulder on the outer wellhead housing 12 that slopes downward and inward and mates with the inner wellhead housing 14 a section of casing 18 is suspended from the inner wellhead housing 14 of the wellhead 10 in an exemplary embodiment the upper casing 18 is a nominal 22 u2033 casing that may extend for example several thousand feet down to a first landing sub 20 below the middle landing sub 20 a middle casing 22 extends downward to a second landing sub 24 a lower casing 26 extends downward from the second landing sub 24 a nominal seat protector u201c nsp u201d is a type of wear bushing that may be inserted into a wellhead component to protect the bore of the wellhead component from damage as drill bits drill pipe etc are passed back and forth though the bore of the wellhead component in the illustrated embodiment an nsp may be deployed within the inner wellhead housing 14 and landing subs 20 24 to protect bore surfaces of the inner wellhead housing and or landing subs a first nsp 30 is illustrated with dashed lines within the inner wellhead housing 14 in addition a second nsp 32 is provided to protect bore surfaces of the first landing sub 20 finally a third nsp 34 is presented in the illustrated embodiment to protect bore surfaces of the second landing sub 24 the minimum inner diameter of the landing shoulder in wellhead housing 14 is greater than the minimum.